Fix Next.js build errors

Most Next.js 15 build failures trace back to a small set of causes: synchronous request-API access, unexpected dynamic rendering, missing 'use client', or removed packages like @next/font. Read the first error's file and component, then fix the root cause.

WorkflowDifficulty: moderatemedium risk

Last verified May 20, 2026 · Updated May 22, 2026

A failing next build usually points at one of a few root causes: a synchronous request API that must be awaited, a route that went dynamic when it should be static, a Server Component using client-only APIs without 'use client', or an import of a removed package. Fix the first error's root cause rather than suppressing it.

Common build errors

'cookies()/headers()/searchParams should be awaited' — sync access to an async request API.
'Route couldn't be rendered statically because it used ...' — unexpected dynamic usage.
'You're importing a component that needs useState/useEffect' — missing 'use client'.
'Module not found: @next/font' — switch to the built-in next/font.

Likely causes

Code written for the Next.js 14 synchronous request APIs.
Reliance on the old fetch/Route Handler caching defaults.
Client-only hooks or browser APIs used inside a Server Component.
Stale dependencies or a removed package still imported.

Diagnostic commands

shell

# Reproduce the real build error$ npm run build# Then read the FIRST error's file path and component stack before changing anything

Test failure debuggingAI debugging prompt

My `next build` fails with this error: <paste the first error and stack>. Identify the root cause (sync request API, unexpected dynamic rendering, missing 'use client', or a removed package) and propose the smallest fix that addresses the cause — await the async API, set explicit caching, add 'use client' to the right boundary, or update the import. Do not disable type checking or ignore the error to make the build pass.

Safety: Never set ignoreBuildErrors or eslint.ignoreDuringBuilds to mask the failure — fix the underlying cause.

Safe fix workflow

Await the flagged async request API (cookies/headers/draftMode/params/searchParams).
Set caching intent explicitly: cache: 'force-cache' or a dynamic/static route config.
Add 'use client' to the smallest component that actually needs client APIs.
Update or remove imports of packages removed in 15 (e.g. @next/font).
Re-run npm run build and confirm the error is gone.

Escalation checklist

Error persists after awaiting the request API and setting caching
A third-party package is the source and has no Next 15 / React 19 build
The failure only reproduces in the production build, not in dev

Official sources

Official docsNext.js Documentationnextjs.orgreliability 98%
Backs the breaking-change and migration-step claims.